Coolant weep around head nut

[mcgarrett]

Noticed coolant weeping around the head nut nearest to the 3 and 4 spark plugs. With the engine running, I could see slight bubbling from the threads. I tried tightening the nut slightly, but didn't want to over-tighten. All head nuts are at 55 lbs. Is there a remedy besides pulling the head? What about block sealer?

[WHN]

You could try radiator sealer.

I would check your engine oil to make sure you don’t have more of a leak than you think.

Good luck.

[Mulletwagon]

Common problem. The fix is to add some aluminized stop leak to the cooling system. Additional torque (beyond spec) on the nuts is not the solution. I went the stop leak route two years ago and have had zero leakage since. Good Luck.

[Synchro909]

The head stud holes are blind until some ham fisted person screws a stud in too tight and breaks it out. I've even found a chunk of CI in the water jacket from this. This leak is caused by such a break. When I find a hole that goes right through into the water jacket, I seal that stud thread when I put it in to avoid this happening.
I woke up to what was happening when I had exactly this same thing happen. Some radiator sealer fixed it for years till I rebuilt the engine, then I sealed the thread with some Permatex #2.

[mcgarrett]

Thanks to all for the helpful comments. I have some aluminized radiator stop leak. I'll give it a dose.

[ABento]

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Don't use the old alum seal powder that stuff gathers and plugs things up, Bars leak came out with a new a few years ago, it is suspended alum in a mix of something in a green bottle, I've had excellent luck with it.
But if the studs are not corroded in the block you could pull the stud and use teflon sealant on it and put it back in.

[nkaminar]

It could be the head gasket leaking next to a coolant passage.

[mcgarrett]

nkaminar
Yeah, I thought about that too. I'm going to try the new Bars Leaks stuff mentioned by ABento above. Nothing to lose and might just cure it.

[Phil Brown]

I just changed to straight water in the cooling system for about 2 weeks, it stopped seeping water so back to the regular coolant. Been good for about 10 years now
Might not be a thing to try right now depending on your location but it is one good thing about living in southern Calif.

[jack backer]

Head studs finger tight, RTV on threads. studs rusting to the head stud bores is the main cause of difficult head removal. Removing the leaking head nut and smearing a little rtv around the stud and retorquing works too.

Finger tight studs in block with RTV on the threads and a light wipe of antisieze compound on the stud shank allows the studs to be removed before the head during the next head gasket replacement, making the head removal and cleaning of the deck a snap..

[Synchro909]

Originally Posted by jack backer

Head studs finger tight, RTV on threads. studs rusting to the head stud bores is the main cause of difficult head removal. Removing the leaking head nut and smearing a little rtv around the stud and retorquing works too.

Finger tight studs in block with RTV on the threads and a light wipe of antisieze compound on the stud shank allows the studs to be removed before the head during the next head gasket replacement, making the head removal and cleaning of the deck a snap..

If RTV is applied every time the stud is screwed in, it will build up in the bottom of the hole over time unless someone is smart enough to clean it out and there are not many people like that. Once there is a buildup in the bottom of the hole, screwing the stud in even to the end of the thread might break out the bottom of the hole.
Unless the hole is already broken out, I don't use silicone on the studs. A drop of oil or a touch of antisieze is the limit.

[nkaminar]

If you are rebuilding an engine, use a bottom tap to clean out the threads in the block. Blow out the crap with high-pressure compressed air gun. A dental pick, available at auto parts stores, can also be used to clean out the bottom of the hole.

[mcgarrett]

Good advice from all. I feel pretty sure using the Bars Leaks as previously mentioned will take care of the problem. I plan to add it to the radiator this week.

[Tacoma Bob]

Whatever you do don't let anyone convince you to use "waterglass" (sodium silicate) I had the same issue and an old timer gave me some to use. It made a mess of my cooling system. I had that crap in there for several years. Some guys swear by it. I swear because of it.

[jack backer]

Attention to detail is critical when doing engine work.Common mechanical sense is assumed. Demanding technical writing for complete novices is beyond the scope of a forum, and is the request of a troll.

[Bob Bidonde]

I have seen coolant leakage at some head nuts many times. These slides show what I have done to fix the leaks.

[mcgarrett]

Bob B,
I didn't know that head studs were to be installed HAND TIGHT. Thanks for that important info.

[1crosscut]

I coat the threads of the studs going into the block with Indian Head shellac.
While still wet I adjust the depth of the studs into the block so the tops of the studs will show the same amount of threads above the head stud nuts.
Allowing it to dry and set before installing the head will generally keep the studs from turning when the head is installed.
Just makes for a nicer looking job when done.

[jack backer]

Hand tight and oiled or sealed. You ‘stretch’ the stud when torquing the head, this stretch locks the nut. The stud thread at zero load allow torque to be applied, tightening the stud in the block isn’t necessary.

[mcgarrett]

Very helpful information indeed. Thanks for sharing.